Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Further, the man who is to handle arguments correctly must know the nature and meaning of everything and their usual effects. For it is thus that we arrive at probable arguments or εἰκότα as the Greeks call them.
With regard to credibility there are three degrees. First, the highest, based on what usually happens, as for instance the assumption that children are loved by
Consequently Aristotle in the second book of his Rhetoric has made a careful examination of all that commonly happens to things and persons, and what things and persons are naturally adverse or friendly to other things or persons, as for instance, what is the natural result of wealth or ambition or superstition, what meets with the approval of good men, what is the object of a soldier's or a farmer's desires, and by what means everything is sought or shunned.